linux-kernel - [PATCH 00/10] KVM: x86: pvclock fixes and cleanups

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Message-ID: <20250118005552.2626804-1-seanjc@google.com>
Date: Fri, 17 Jan 2025 16:55:42 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	David Woodhouse <dwmw2@...radead.org>, Paul Durrant <paul@....org>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzbot+352e553a86e0d75f5120@...kaller.appspotmail.com, 
	Paul Durrant <pdurrant@...zon.com>, David Woodhouse <dwmw@...zon.co.uk>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH 00/10] KVM: x86: pvclock fixes and cleanups

Fix a lockdep splat in KVM's suspend notifier by simply removing a
spurious kvm->lock acquisition related to kvmclock, and then try to
wrangle KVM's pvclock handling into something approaching sanity (I
made the mistake of looking at how KVM handled PVCLOCK_GUEST_STOPPED).

David,

I didn't look too closely to see how this interacts with your overhaul of
the pvclock madness[*].  When I first started poking at this, I didn't
realize vcpu->arch.hv_lock had tendrils in so many places.  Please holler
if you want me to drop the vcpu->arch.hv_lock changes and/or tweak
something to make it play nice with your series.

The Xen changes are *very* lightly tested, so I definitely won't apply
the potentially problematic changes, i.e. anything past "Don't bleed
PVCLOCK_GUEST_STOPPED across PV clocks", until I get a thumbs up from
you and/or Paul.

[*] https://lore.kernel.org/all/20240522001817.619072-1-dwmw2@infradead.org

Sean Christopherson (10):
  KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend
    notifier
  KVM: x86: Eliminate "handling" of impossible errors during SUSPEND
  KVM: x86: Drop local pvclock_flags variable in kvm_guest_time_update()
  KVM: x86: Set PVCLOCK_GUEST_STOPPED only for kvmclock, not for Xen PV
    clock
  KVM: x86: Don't bleed PVCLOCK_GUEST_STOPPED across PV clocks
  KVM: x86/xen: Use guest's copy of pvclock when starting timer
  KVM: x86: Pass reference pvclock as a param to
    kvm_setup_guest_pvclock()
  KVM: x86: Remove per-vCPU "cache" of its reference pvclock
  KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock
    update)
  KVM: x86: Override TSC_STABLE flag for Xen PV clocks in
    kvm_guest_time_update()

 arch/x86/include/asm/kvm_host.h |   3 +-
 arch/x86/kvm/x86.c              | 115 ++++++++++++++++----------------
 arch/x86/kvm/xen.c              |  62 +++++++++++++++--
 3 files changed, 114 insertions(+), 66 deletions(-)

base-commit: eb723766b1030a23c38adf2348b7c3d1409d11f0
-- 
2.48.0.rc2.279.g1de40edade-goog